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Server Gurus Discussions

ksistof_bortkevic
Journeyman III

Epyc 7282 Memory bandwidth issues

Hello,

We seem to be having a problem with memory bandwidth using 2 Epyc 7282 CPUs with 4 DIMMS of HMA82GR7CJR8 RAM 16GB DDR4-3200 2Rx8 ECC REG DIMM HYNIX memory per socket on a Supermicro H11DSi board. We tried a couple of different benchmarks on Windows an Linux, they show the RAM Bandwidth as ~20 GB/s. We tried playing around with the BIOS settings and managed to get to ~30-40 GB/s. There are 4 DIMMs per socket, and some layouts work better than others. With one CPU and 8 DIMMs we get ~60 GB/s. Can anyone assist us with this issue?

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3 Replies
hardcoregames_
Big Boss

Re: Epyc 7282 Memory bandwidth issues

The AMD specs for your processor show it is designed for DDR4-3200 

https://www.amd.com/en/products/cpu/amd-epyc-7282 

I suggest changing to that memory timings a tad and see if your able to reduce the latency. Try this idea and I can help you squeeze more out of your server than those posted values

No disrespect, my desktop blows your server away for memory bandwidth.

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arjunsuresh
Journeyman III

Re: Epyc 7282 Memory bandwidth issues

Please see here for how to configure the RAM chips. You should be able to get 120 GBps if 8 DIMMs are configured to 8 memory channels across the 2 sockets. 

https://developer.amd.com/wp-content/resources/56301_1.0.pdf

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111alan
Adept I

Re: Epyc 7282 Memory bandwidth issues

When you use EPYC always fill up all the memory channels or there's a high chance for the bandwidth to bug out. I experienced this issue several times with 7702 and 7742 on H11SSL where 4-6 channels only get up to 3-40GB/s.

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